To filter documents based on an array, use $elemMatch. The $elemMatch operator matches documents that contain an array field.Let us create a collection with documents −> db.demo453.insertOne( ... { _id: 101, details: [ { Name: "David", Marks: 60 }, { Name: "Mike", Marks: 55} ] } ... ) { "acknowledged" : true, "insertedId" : 101 } > db.demo453.insertOne( ... { _id: 102, details: [ { Name: "Bob", Marks: 80 }, { Name: "Sam", Marks: 78} ] } ... ) { "acknowledged" : true, "insertedId" : 102 } > db.demo453.insertOne( ... { _id: 103, details: [ { Name: "Carol", Marks: 67 ... Read More

To get the count of repeated values in different documents, use aggregate(). Let us create a collection with documents −> db.demo452.insertOne({"StudentName":"John", "StudentAge":21});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b7e3371f552a0ebb0a6f3") } > db.demo452.insertOne({"StudentName":"John", "StudentAge":22});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b7e3671f552a0ebb0a6f4") } > db.demo452.insertOne({"StudentName":"John", "StudentAge":23});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b7e3971f552a0ebb0a6f5") } > db.demo452.insertOne({"StudentName":"David", "StudentAge":24});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b7e4371f552a0ebb0a6f6") } > db.demo452.insertOne({"StudentName":"David", "StudentAge":25});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b7e4571f552a0ebb0a6f7") }Display all documents from a collection with the help of find() method −> db.demo452.find();This will produce the following output −{ "_id" : ... Read More

To get the mean daily average count of recorded documents, use aggregate(). Within that, use $project and $group.Let us create a collection with documents −Example> db.demo451.insertOne({ ... DueDate:new ISODate("2020-03-15T10:50:35.000Z"), ... Value: 10 ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e7b5c5d71f552a0ebb0a6e9") } > db.demo451.insertOne({ ... DueDate:new ISODate("2020-03-14T10:50:35.000Z"), ... Value: 10 ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e7b5c5d71f552a0ebb0a6ea") } > db.demo451.insertOne({ ... DueDate:new ISODate("2020-03-13T10:50:35.000Z"), ... Value: 10 ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e7b5c5d71f552a0ebb0a6eb") }Display all documents from a collection with the help of find() ... Read More

In order to reach subdata, you need to use key in MongoDB. Let us create a collection with documents −>db.demo450.insertOne({"Information":{"StudentDetails":{"StudentName":"Chris", "StudentAge":21}}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e7b590e71f552a0ebb0a6e6") } >db.demo450.insertOne({"Information":{"StudentDetails":{"StudentName":"David", "StudentAge":23}}});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b591a71f552a0ebb0a6e7") } >db.demo450.insertOne({"Information":{"StudentDetails":{"StudentName":"Mike", "StudentAge":22}}});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b592271f552a0ebb0a6e8") }Display all documents from a collection with the help of find() method −> db.demo450.find();This will produce the following output −{ "_id" : ObjectId("5e7b590e71f552a0ebb0a6e6"), "Information" : { "StudentDetails" : { "StudentName" : "Chris", "StudentAge" : 21 } } } { "_id" : ObjectId("5e7b591a71f552a0ebb0a6e7"), "Information" : { "StudentDetails" : { ... Read More

To insert an item to an already created array inside an object, use MongoDB $push. Let us create a collection with documents −> db.demo449.insertOne( ... { ...    details1: { ...       details2: [{ ...          _id:new ObjectId(), ...             Name:"Chris" ...       }], ...       details3: [{ ...          _id:new ObjectId(), ...          Name:"David" ...       }] ...    } ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e7a40e971f552a0ebb0a6e3") }Display all documents from ... Read More

The findOneAndDelete() deletes single documents from the collection on the basis of a filter and sort criteria as well as it returns the deleted document.The deleteOne() removes single document from the collection.Let us see an example and create a collection with documents −> db.demo448.insertOne({"Name":"Chris", "Age":21});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7a291cbbc41e36cc3caeca") } > db.demo448.insertOne({"Name":"David", "Age":23});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7a2926bbc41e36cc3caecb") } > db.demo448.insertOne({"Name":"Bob", "Age":22});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7a2930bbc41e36cc3caecc") }Display all documents from a collection with the help of find() method −> db.demo448.find();This will produce the following output −{ "_id" : ObjectId("5e7a291cbbc41e36cc3caeca"), ... Read More

Data scientists, data engineers, and data analysts are all professionals who work with data in some way. However, they have different roles and responsibilities. Read this article to find out more the job profiles of data scientists, data engineers, and data analysts and how you can distinguish among them. Who is a Data Scientist? A Data Scientist is one who analyses and interprets complex data in digital form. Data scientists are responsible for extracting insights and knowledge from data. They use a variety of techniques, including machine learning, to analyze data and communicate their findings to stakeholders. There are several ... Read More

For this, you can use $lookup. Let us create a collection with documents −> db.demo446.insert([ ...    { "ProductName": "Product1", "ProductPrice": 60 }, ...    { "ProductName": "Product2", "ProductPrice": 90 } ... ]) BulkWriteResult({    "writeErrors" : [ ],    "writeConcernErrors" : [ ],    "nInserted" : 2,    "nUpserted" : 0,    "nMatched" : 0,    "nModified" : 0,    "nRemoved" : 0,    "upserted" : [ ] })Display all documents from a collection with the help of find() method −> db.demo446.find();This will produce the following output −{ "_id" : ObjectId("5e790766bbc41e36cc3caec3"), "ProductName" : "Product1", "ProductPrice" : 60 } { ... Read More

To push into an array with MongoDB, use $push. Let us create a collection with documents −> db.demo445.insertOne({"ListOfFriends":["Robert", "Mike", "Sam", "Carol", "David", "Mike"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e78f099bbc41e36cc3caec2") }Display all documents from a collection with the help of find() method −> db.demo445.find().pretty();This will produce the following output −{    "_id" : ObjectId("5e78f099bbc41e36cc3caec2"),    "ListOfFriends" : [       "Robert",       "Mike",       "Sam",       "Carol",       "David",       "Mike"    ] }Following is the query to push into an array −> db.demo445.update( ...    { ... Read More

For this, use $elemMatch, which is used to query nested objects. Let us create a collection with documents −> db.demo444.insertOne( ...    { ...       "Information": [{ ...          id:1, ...          Name:"Chris" ...       }] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e78ea87bbc41e36cc3caebf") } > db.demo444.insertOne( ...    { ...       "Information": [{ ...          id:2, ...          Name:"David" ...       }] ...    } ... ); {    "acknowledged" : true,   ... Read More